Power supply/demand control system

ABSTRACT

In order to effectively supply and demand electric power between an electric power supplier and a node or a group of nodes individually having an electric power generator, the present invention provides an electric power supply and demand management system capable of obtaining the difference between the total of electric power supplied from the electric power supplier to the node or group and the total of electric power consumed by the electric power loads of the node or group and capable of transmitting information for increasing/decreasing the amount of electric power supply so that the difference becomes smaller to the electric power supplier.

TECHNICAL FIELD

[0001] The present invention relates to a distributed electric powergeneration system comprising an electric supplier and consumers forefficiently controlling and managing the supply and demand of electricpower.

BACKGROUND ART

[0002] In recent years, energy-saving measures have been takensignificantly in view of environmental protection including theprevention of the greenhouse effect owing to carbon dioxide, althoughnot so significantly as those during the oil crisis owing to oilshortage. Consumers of electric power are classified into industrialconsumers and household consumers; the electric power consumption by theindustrial consumers stays almost constant after 1970s, but the electricpower consumption by the household consumers has increased twice or moreafter 1970s. Hence, additional energy-saving measures are required to betaken for household consumers.

[0003] At present, the great majority of electric power generated byelectric power supplier sides, such as hydraulic, thermal and atomicelectric power generation, is transmitted by a system comprisingelectric power transmission lines, substations, etc. and supplied toconsumer sides, such as households and factories. In this kind of largeelectric power generation system, heat generating simultaneously withelectric power generation cannot be used, and the loss of electric powertransmission from electric power stations to consumers is large, wherebythe final energy efficiency is low. Particularly in household consumershaving many distributed loads with low amount of electric powerconsumption, energy efficiency becomes low.

[0004] For this reason, attention is paid recently to the so-calleddistributed electric power generation, that is, electric powergeneration by small-scale electric power generators near electric powerconsumption regions, and in particular, attention is paid tocogeneration-type electric power generation wherein electric power isgenerated by a gas turbine or a fuel cell and waste heat generatedduring electric power generation can also be used.

[0005] In this kind of distributed electric power generation, each ofnodes, such as a household, a factory, a company, a building and aschool, itself has an electric power generator, and the node purchaseslacking electric power from an outside commercial electric power system(an electric power company, an electric power supplier or the like) andsells extran electric power to an electric power supplier, therebyperforming the so-called “trading of electric power.”

[0006] Even in this kind of distributed electric power generation, ifthe sale of electric power to a commercial electric power system iscarried out regardless of the present electric power demand, atransmission loss occurs in the case when a node that sells electricpower is distant from an electric power supplier who purchases theelectric power; however, conventionally, electric power should only begenerated at one location and transmitted efficiently to locations nearconsumers; hence, if contractors who sell electric power are few, thetransmission system is not affected greatly.

[0007] However, if each node sells extran electric power, transmissioncost changes greatly depending on the distributions of electric powerselling locations and electric power consuming locations. Accordingly,the present invention is intended to provide an electric power supplyand demand management system capable of reducing the transmission lossand controlling and managing the supply and demand of electric powerefficiently by selecting a node that can sell electric power from theelectric power generator thereof the anode to an electric power supplierdepending on the demand at the other nodes.

[0008] Furthermore, when a fuel cell is used as an electric powergenerator at the node, a time lag of at least one to two hours occursuntil a fuel gas, such as hydrogen or propane gas, and oxygen aresupplied to the fuel cell and then electric power generation starts. Forthis reason, when electric power is generated at a node, such as adwelling house, wherein electric power demand greatly changes dependingon time, season, or the like, the amount of electric power generated bythe fuel cell cannot be controlled promptly depending on the change inthe electric power demand at the node, whereby generated electric powerbecomes excessive or lacking. This causes a problem, that is, theabove-mentioned node must purchase lacking electric power from theoutside in spite of having an electric power generator or sell excessiveelectric power to the outside.

[0009] Accordingly, the present invention is intended to provide anelectric power supply and demand management system capable of allowing afuel cell used as an electric power generator to generate an appropriateamount of electric power, not excessive nor lacking, depending on thesupply and demand at each node.

DISCLOSURE OF INVENTION

[0010] The present invention relates to an electric power supply anddemand management system including an electric power supplier, anelectric power transmission system, and electric power consuming nodes,each of which having an electric power generator, connected to theelectric power transmission system and classified into a plurality ofgroups, characterized by comprising, a first calculation unit forobtaining a difference between a total of electric power supplied fromthe electric power supplier to the node or group and a total of electricpower consumed by an electric power load of the node or group, and afirst transmission unit for transmitting information forincreasing/decreasing an amount of electric power supply to the electricpower supplier so that the difference becomes smaller.

[0011] It is effective that the first calculation unit determines atleast one of a selling price of electric power from the electric powersupplier to the node or group and a purchase price of electric powerfrom the node or the group to the electric power supplier, by using thedifference between a total of electric power supply from the electricpower supplier to the node or group and a total of electric powerconsumed by an electric power load at the node or group as a parameter,and the first transmission unit transmits at least one of the sellingprice and the purchase price to the node or group.

[0012] It is effective that the electric power supplier has a receptionunit for receiving information selected from the group consisting of anelectric power charge, an amount of electric power consumption and anelectric power supply capacity of the node or the group, the firstcalculation unit determines an amount of electric power and a purchaseprice of electric power demanded by the electric power supplier for eachnode, which can sell electric power among the nodes, on the basis of theinformation, and the first transmission unit transmits at least one ofthe amount of electric power and the purchase price demanded by theelectric power supplier to the node.

[0013] It is effective that the node or the group is provided with; asecond transmission unit for transmitting information selected from thegroup consisting of an electric power charge, an amount of electricpower consumption and an electric power supply capacity to other nodes,groups or the electric power supplier; a second reception unit forreceiving information selected from the group consisting of an amount ofelectric power, a purchase price of electric power and a selling priceof electric power demanded by the other nodes, groups or the electricpower supplier; and a control unit for controlling an output of theelectric power generator of the node on the basis of the information.

[0014] It is effective that the electric power supply and demandmanagement system comprises a node information storage unit for storingnode information including a node identifier for identifying the nodeand an amount of electric power consumption and an amount of electricpower supply of the node identified by the identifier, and that thefirst calculation unit calculates an amount of transmittable electricpower from one node to other nodes and/or the electric power supplier byusing the amount of electric power consumption and the amount ofelectric power supply included in the node information as parameters,the first transmission unit transmits a signal indicating the amount oftransmittable electric power to each node, and the node transmits thetransmittable electric power to the other nodes and/or the electricpower supplier.

[0015] It is effective that the electric power supplier has asubstation, the first calculation unit calculates a purchase amount ofelectric power and a purchase price of electric power, which aredemanded by the electric power supplier, by using electric power supplyand demand information regarding a flowing direction and an amount ofenergy between a high-voltage side to a low-voltage side of thesubstation, and the first transmission unit transmits the amount ofelectric power to be purchased and the purchase price to the node or thegroup.

[0016] It is effective that the node is provided with a storage battery,and a second calculation unit for determining at least one selected fromthe group consisting of a purchase amount of electric power, a purchaseprice of electric power, a selling amount of electric power and aselling price of electric power, which are demanded for the other nodes,by using information regarding electric power demand and storage amountsof storage batteries connected to other nodes, and the secondtransmission unit transmits at least one selected from the groupconsisting of a purchase amount of electric power, a purchase price ofelectric power, a selling amount of electric power and a selling priceof electric power to at least one of the electric power supplier and theother nodes.

[0017] It is effective that the first calculation unit or the secondcalculation unit predicts an amount of electric power consumption at thenode or the group and determines an amount of electric power supply,which is demanded by the node or the group, by using the predicted theamount of electric power consumption as a parameter, and the firsttransmission unit or the second transmission unit transmits a signal inorder for an electric power generator of a node or a group other thanthe node or the group, or for the electric power supplier to supply theamount of electric power.

[0018] It is effective that the electric power supply and demandmanagement system comprises further electric power consumption amountstorage means for storing information regarding an amount of electricpower consumption at each node, and that the first calculation unit orthe second calculation unit predicts an amount of electric powerconsumption at each node or each group by using the stored amount ofelectric power consumption as a parameter.

[0019] It is effective that the first calculation unit or the secondcalculation unit determines an amount of electric power supply from thenode by using data including a relation between an output of theelectric power generator and an amount of fuel consumption asparameters.

[0020] It is effective that the first calculation unit or the secondcalculation unit determines an amount of electric power supply from theelectric power generator by using at least the amount of electric powerconsumption at the node as a parameter.

[0021] It is effective that the first calculation unit or the secondcalculation unit determines an amount of electric power supply of eachelectric power generator so that the number of electric power generatorsin operation of the nodes becomes minimum or maximum.

[0022] It is effective that the first calculation unit or the secondcalculation unit predicts an amount of electric power consumption ateach node by using schedule information.

[0023] It is effective that the first transmission unit or the secondtransmission unit transmits information for increasing/decreasing anamount of electric power supply from the storage battery of the eachnode or the electric power generator connected to the storage battery toa node, which requires electric power, by using information regarding astorage amount of the storage battery or information regarding atransfer amount of energy of each node.

BRIEF DESCRIPTION OF DRAWINGS

[0024]FIG. 1 is a view showing the configuration of an electric powersupply and demand management system in accordance with Embodiment 1 ofthe present invention.

[0025]FIG. 2 is a view showing the configuration of an electric powersupply and demand management system in accordance with Embodiment 2 ofthe present invention.

[0026]FIG. 3 is a view showing the configuration of an electric powersupply and demand management system in accordance with Embodiment 3 ofthe present invention.

[0027]FIG. 4 is an example of a table of bid information including theidentification numbers of nodes, selling price of electric power andselling amount of electric power.

[0028]FIG. 5 is a view showing the configuration of an electric powersupply and demand management system in accordance with Embodiment 4 ofthe present invention.

[0029]FIG. 6 is a view showing the configuration of an example of acircuit for accurately measuring voltage.

[0030]FIG. 7 is a view showing the configuration of an electric powersupply and demand management system in accordance with Embodiment 5 ofthe present invention.

[0031]FIG. 8 is a view showing an example of a table of the amount ofelectric power consumption memorized in storage means in every timezone.

[0032]FIG. 9 is the flowchart of a program for determining the operationof a CPU.

[0033]FIG. 10 is an example of data representing the relation betweenthe output of an electric power generator and the usage amount of fuel.

BEST MODE FOR CARRYING OUT THE INVENTION

[0034] The present invention relates to an electric power supply anddemand management system provided with an electric power supplier astypified by an electric power company, an electric power transmissionsystem, electric power generators and electric power consuming nodesconnected to the above-mentioned electric power transmission system andclassified into a plurality of groups, and further provided with a firstcalculation unit for obtaining the difference between the total ofelectric power supplied from the electric power supplier to the node orthe group and the total of electric power consumed by the electric powerload of the node or the group and a first transmission unit fortransmitting information for increasing/decreasing the amount ofelectric power supply so that the difference becomes smaller to theelectric power supplier. Namely, the present invention relates to asystem for managing the supply and demand of electric power between anelectric power company and consumers having their own electric powergenerators.

[0035] The first calculation unit is mainly used to function for theelectric power supplier and may be provided for any one of the electricpower supplier, the electric power transmission system and the electricpower consuming node. Furthermore, the first calculation unit may beprovided for each group including a plurality of nodes.

[0036] When the information for increasing/decreasing the amount ofelectric power supplied so that the difference between the total ofelectric power supplied from the electric power supplier to the node orgroup and the total of electric power consumed by the electric powerload of the node or group becomes smaller can be sent from the firsttransmission unit to the electric power supplier as described above,electric power generation at the electric power supplier can be carriedout efficiently, thereby it is so effective. The electric power loadmeans one or more electric power consuming apparatuses includingelectric appliances, such as a refrigerator, a washing machine, an airconditioner and a television set.

[0037] Next, it is effective that the first calculation unit determinesat least one of a selling price of electric power from the electricpower supplier to the node or the group and a purchase price of electricpower from the node of the group to the electric power supplier, byusing the difference between a total of electric power supply from theelectric power supplier to the node or the group and a total of electricpower consumed-by an electric power load at the node or the group as aparameter, and the first transmission unit transmits at least one of theselling price and the purchase price to the node or the group.

[0038] With this, each node or group, that is a consumer side, canpurchase lacking electric power promptly and securely, and electricpower additionally stocked in its electric power generator can bepurchased by other nodes or the electric power supplier without wastingsuch an electric power, whereby the electric power supplier can managethe supply and demand of electric power efficiently.

[0039] Furthermore, it is effective that the electric power supplier hasa reception unit for receiving information selected from the groupconsisting of an electric power charge, an amount of electric powerconsumption and an electric power supply capacity of the node or thegroup, the first calculation unit determines an amount of electric powerand a purchase price of electric power demanded by the electric powersupplier for each node, which can sell electric power among the nodes,on the basis of the information, and the first transmission unittransmits at least one of the amount of electric power and the purchaseprice demanded by the electric power supplier to the node.

[0040] With this configuration, depending on the actual condition ofeach node or group, electric power excessively generated by its electricpower generator or stocked therein can be purchased by the electricpower supplier without wasting the electric power, whereby the electricpower supplier can manage the supply and demand of electric power moreefficiently.

[0041] Hence, it is effective that the node or the group is providedwith; a second transmission unit for transmitting information selectedfrom the group consisting of an electric power charge, an amount ofelectric power consumption and an electric power supply capacity to theoutside (other nodes, groups or said electric power supplier); a secondreception unit for receiving information selected from the groupconsisting of an amount of electric power, a purchase price of electricpower and a selling price of electric power demanded by the outside; anda control unit for controlling an output of the electric power generatorof the node on the basis of the information.

[0042] In this way, if each node or group transmits the informationselected from the group consisting of the electric power charge, theamount of electric power consumption and the electric power supplycapacity to the outside by using the second transmission unit, the nodeor group can receive the information selected from the group consistingof the purchase price of electric power and the selling price ofelectric power from the outside by using the second reception unit,thereby the electric power generator thereof can be controlled securelywithout causing waste.

[0043] It is effective that the electric power supply and demandmanagement system is provided with a node information storage unit forstoring node information including a node identifier for identifying thenode and an amount of electric power consumption and an amount ofelectric power supply of the node identified by the identifier, and thatthe first calculation unit calculates an amount of transmittableelectric power from one node to other nodes and/or the electric powersupplier by using the amount of electric power consumption and theamount of electric power supply included in the node information asparameters, the first transmission unit transmits a signal indicatingthe amount of transmittable electric power to each node, and the nodetransmits the transmittable electric power to the other nodes and/or theelectric power supplier.

[0044] The above-mentioned node information storage unit may only be theso-called storage unit and may be provided for any one or more of thenode, the group and the electric power supplier, and is mainlycontrolled by the above-mentioned electric power supplier. Furthermore,this node information storage unit is connected to the first calculationunit of the electric power supplier, and the first calculation unitcalculates the amount of transmittable electric power from one node toother nodes by using the amount of electric power consumption and theamount of electric power supply included in the node information asparameters, whereby the amount of transmittable electric power can betransmitted from the one node to the other nodes. In other words,electric power generated or stocked excessively at each node can be usedeffectively at other nodes.

[0045] The electric power supplier may have a substation. In this case,it is effective that the first calculation unit calculates a purchaseamount of electric power and a purchase price of electric power, whichare demanded by the electric power supplier, by using electric powersupply and demand information regarding a flowing direction and anamount of power (energy) between a high-voltage side to a low-voltageside of the substation, which may be measured by a magnetic field forexample, and that the first transmission unit transmits the amount ofelectric power to be purchased and the purchase price to the node.

[0046] Hence, the electric power supplier can effectively use electricpower depending on the condition of the substation thereof and the likeand can effectively control the substation.

[0047] In addition, the node should preferably have a storage battery.In this case, each node can stock electric power by itself and canexamine the selling time of the stocked electric power depending on thechange in the price of electric power in the market including the othernodes and/or the electric power supplier.

[0048] In this case, it is effective that each node is provided with asecond calculation unit for determining at least one selected from thegroup consisting of a purchase amount of electric power, a purchaseprice of electric power, a selling amount of electric power and aselling price of electric power, which are demanded for the other nodes,by using information regarding electric power demand and storage amountsof storage batteries connected to other nodes, because the secondtransmission unit can transmit the demanded amount of electric power andthe purchase price of electric power to at least one of the electricpower supplier and the other nodes.

[0049] Furthermore, it is effective that the first calculation unit orthe second calculation unit predicts the amount of electric powerconsumption at a predetermined node or group and determines the amountof electric power supply to the predetermined node or group by using thepredicted amount of electric power consumption as a parameter, and thatthe transmission unit or second transmission unit transmits a signal inorder for to the electric power generator of a node or group other thanthe predetermined node or group to supply the amount of electric power.

[0050] In this case, it is effective that the electric power supply anddemand management system is provided with electric power consumptionamount storage means for storing information regarding an amount ofelectric power consumption of each node, and that the first calculationunit or the second calculation unit predicts an amount of electric powerconsumption of each node or each group by using the stored amount ofelectric power consumption as a parameter. The electric powerconsumption amount storage means may be provided at each node or theelectric power supplier, or the node information storage unit mayfunction as the electric power consumption amount storage means.

[0051] Moreover, it is effective that the first calculation unit or thesecond calculation unit determines the amount of electric power supplyfrom the node by using data including the output of the electric powergenerator and the amount of fuel consumption required for the output asparameters.

[0052] Still further, it is effective that the first calculation unit orthe second calculation unit determines the amount of electric powersupply from the electric power generator by using at least the amount ofelectric power consumption at the node as a parameter.

[0053] It is effective that the first calculation unit or the secondcalculation unit determines the amount of electric power supply of eachelectric power generator so that the number of electric power generatorsin operation at the node becomes minimum or maximum.

[0054] It is effective that the first calculation unit or the secondcalculation unit predicts the amount of electric power consumption ateach node by using information regarding the schedule of the componentsor the electric power consuming apparatuses at each node.

[0055] It is effective that, by using the storage amount of the storagebattery or the transfer amount of electric power at each node, the firsttransmission unit or the second transmission unit transmits informationfor increasing/decreasing the amount of electric power supplied from thestorage battery at the each node or the electric power generatorconnected to the storage battery to a node requiring the electric power.One calculation unit may function as the first calculation unit and thesecond calculation unit.

[0056] Hence, in the electric power supply and demand management systemin accordance with the present invention, the electric power suppliermay have the substation and the control unit in addition to the firstcalculation unit and the first transmission unit, and each node may havethe second calculation unit, the second transmission unit, the storagebattery and the control unit in addition to the electric powergenerator. The node information storage unit and the electric powerconsumption amount storage means may be provided anywhere if they arecommunicated electrically with each other.

[0057] All of these components are at least electrically connected andconstitute the electric power supply and demand management system inaccordance with the present invention. Furthermore, the electric powersupply and demand management system in accordance with the presentinvention should only be provided with the minimum componentscorresponding to at least the functions and effects. Hence, componentscapable of attaining predetermined functions and effects can be combinedappropriately, and the system may preferably have all the components.

[0058] Although typical examples of the electric power supply and demandmanagement system in accordance with the present invention will bedescribed below more specifically referring to the accompanyingdrawings, the present invention is not limited only thereto.

[0059] Embodiment 1

[0060] Next, preferable embodiment in accordance with the presentinvention will be described referring to the drawings.

[0061]FIG. 1 is a view showing the configuration of an electric powersupply and demand management system in accordance with Embodiment 1 ofthe present invention. The electric power supply and demand managementsystem shown in FIG. 1 comprises an electric power supplier 1, n (n≧2)nodes 2 and an electric power transmission system 3, and the node 2 hasan electric power generator 4, such as a fuel cell, a storage battery 5,and electric power consuming apparatuses 6, such as a refrigerator, awashing machine, an air conditioner and a television set, wherebytemporary excessive or lacking electric power can be adjusted by thestorage battery 5.

[0062] The electric power supplier 1 has a first calculation unit 1 afor obtaining the difference between the total of electric powersupplied from the electric power supplier 1 to the node 2 (or a group ofa plurality of nodes 2) and the total of electric power consumed byelectric power load at the node 2 (or a group of a plurality of nodes 2)and a first transmission unit for transmitting information forincreasing/decreasing the amount of electric power supply so that thedifference becomes smaller to the electric power supplier. Hence, theelectric power supplier can efficiently control its own electric powergeneration.

[0063] In addition, by using the difference between the total ofelectric power supplied from the electric power supplier to the node orgroup and the total of electric power consumed by electric power load atthe node or group as a parameter, the first calculation unit determinesat least one of the selling price of electric power from the electricpower supplier to the node or group and the purchase price of electricpower from the node or group to the electric power supplier, and thefirst transmission unit transmits at least one of the selling price andpurchase price to the node or group.

[0064] The storage battery 5 has an electric power storage unit forstoring electric power and an electric power management unit (not shown)for managing the amount of the electric power stored in the electricpower storage unit; the electric power management unit monitors thecurrent flowing through the electric power storage unit, grasps electricpower amount information, that is, information regarding the amount ofelectric power storage, and transmits the electric power amountinformation to an electric power selling/purchasing system 7. Hence, theelectric power selling/purchasing system 7 may include a control unit, asecond calculation unit, a second transmission unit and a secondreception unit.

[0065] Furthermore, the electric power selling/purchasing system 7receives the electric power storage amount of the storage battery andtransmits the identification number of the node to which the system itself belongs, a salable amount of electric power, etc. to the electricpower transmission system 3 by using small pulses. Moreover, a meter 8provided for electric power lines led from electric power transmissionlines constituting the electric power transmission system 3 into thenode 2 transmits information regarding the identification number of thenode 2, the salable amount of electric power and the purchasable amountof electric power (in other words, transfer amount information regardingthe transfer amount of energy) to the electric power transmission system3 by using small pulses. This meter 8 may be included in the electricpower selling/purchasing system 7 as a matter of course.

[0066] The information transmitted by the electric powerselling/purchasing system 7 used as the second transmission unit and themeter 8 is transmitted to other nodes, the above-mentioned group or theelectric power supplier 1, and the electric power selling/purchasingsystem 7 finds out a node outputting an information signal meaning thatelectric power can be sold in accordance with the above-mentionedtransmitted information near the node, from which electric power ispurchased and transmits electric power selling request information (therequest amount of electric power supply) to the node. For example,information regarding the identification number of the node requestingthe selling of electric power and the amount of electric power requestedto be sold is transmitted to the electric power transmission lines byusing small pulses.

[0067] Furthermore, the electric power selling/purchasing system 7monitors the pulses transmitted to the electric power transmissionlines; when the electric power selling/purchasing system detects theidentification number of the node to which the system itself belongs, ittransmits the information subsequent thereto. If the information iselectric power selling request information, electric power istransmitted to the electric power transmission lines in accordance withthe information.

[0068] In the above-mentioned embodiment, the information transmitted bythe electric power selling/purchasing system 7 is the electric powerstorage amount of the storage battery; however, without being limited tothe electric power storage amount, the extra capacity of the electricpower generator (the value obtained by subtracting the amount ofelectric power consumption predicted at present or in the future fromthe maximum output or the most efficient output of the electric powergenerator) may be transmitted. Both may also be transmitted as a matterof course.

[0069] Moreover, the available capacity of the storage battery (theamount of electric power that can be stored further in the storagebattery, in other words, (the capacity of the storage battery)−(theelectric power storage amount of the storage battery)), may betransmitted so that the selling of electric power from a node, in whichits storage battery becomes full and its electric power is highlyunlikely to be used effectively, has higher priority.

[0070] Still further, the capacity of the storage battery may bememorized in advance in an apparatus for determining the amount ofelectric power, which is sold by each anode, and both the value of theelectric power storage amount and the available capacity of the storagebattery may be used as information regarding the electric power storageamount of the storage battery to determine the amount of electric powerto be sold from each node. If the available capacity of the storagebattery is known, the amount of electric power unable to be stored inthe storage battery and thus wasted can be reduced.

[0071] Still further, each node 2 is not always required to have thestorage battery 5. When the node does not have the storage battery 5,electric power selling request information may be formed by usinginformation regarding the electric power generator 4, such as the extracapacity of the electric power generator 4.

[0072] Still further, a node without the electric power generator 4 mayalso be used. In this case, the node should only be dealt with such thatits salable amount of electric power is zero. In addition, in theabove-mentioned embodiment, the salable amount of electric power and thepurchasable amount of electric power (in other words, transfer amountinformation regarding the transfer amount of energy) to be transmittedfrom the meter 8 and the information regarding the salable amount ofelectric power (in other words, information regarding the electric powerstorage amount of the storage battery) to be transmitted from theelectric power selling/purchasing system 7 are transmitted separately;however, both may be transmitted together by means of the electric powerselling/purchasing system 7 and information can be transmittedefficiently by such a transmission.

[0073] Still further, in the above-mentioned embodiment, a signalindicating the amount of electric power that can be supplied istransmitted as information regarding the electric power supply capacity;however, only the information as to whether electric power can besupplied or not may be transmitted as information regarding electricpower supply capacity from the anode 2, and only the information as towhether electric power is permitted to be sold or not may be received atthe anode 2 as information for increasing/decreasing the electric powersupply capacity.

[0074] Still further, in the above-mentioned embodiment, information istransmitted via the electric power transmission system by using theelectric power transmission lines; however, without being limitedthereto, the telephone lines, wireless transmission or the lines of ACelectric power sources may also be used, for example. When using theelectric power transmission lines, the lines are advantageous since itis not necessary to prepare new transmission lines and the like. On theother hand, when not using the electric power transmission lines, thismethod is advantageous since information transmission is possible evenwhen the electric power transmission lines are affected by trouble, suchas a thunderbolt.

[0075] Embodiment 2

[0076]FIG. 2 is a view showing the configuration of an electric powersupply and demand management system in accordance with Embodiment 2 ofthe present invention. In FIG. 2, electric power transmission lines 40are high-voltage electric power transmission lines and have a highvoltage in order to efficiently transmit electricity from an electricpower supplier, such as a thermal electric power station, to nodes 2,such as residential areas. Electric power transmission lines 50 andelectric power transmission lines 150 are transmission lines fortransmitting a voltage to be supplied to each node; for example, thevoltage is controlled so as to be maintained at a constant voltage inthe range of about 100 to 220 V.

[0077] A substation 10 belonging to the electric power supplier isprovided between the electric power transmission lines 40 and theelectric power transmission lines 50 and transforms the voltage acrossthe electric power transmission lines 40 to the voltage across theelectric power transmission lines 50. The relation between the electricpower transmission lines 40 and the electric power transmission lines150 is similar to that described above. To the substation 10, 99 numbersof nodes 2 are connected, whereby electric power can be sold orpurchased. The amount of electric power transformed by the substationcan be measured by an ammeter 20, and the result of the measurement (inother words, electric power demand information regarding the movementdirection and the amount of electric energy flowing through the electricpower transmission lines) is sent to a salable electric power pricesetting apparatus 30. This ammeter 20 and the price setting apparatus 30constitute the first calculation unit or the second calculation unit.

[0078] When energy flows from the electric power transmission lines 50to the electric power transmission lines 40, the price setting apparatus30 lowers the selling price of electric power having been set at present(in other words, information for increasing/decreasing the amount ofelectric power to be sold by each node), and notifies the price to the99 numbers of nodes 2. In the case when the electric power generationcost at the node 2 itself is higher than the selling cost of theelectric power, the output of its electric power generator is lowered orthe electric power generator is stopped, whereby the sale of electricpower can be stopped. This can prevent the sale of electric power from aregion to which electricity is supplied from the substation 10.

[0079] On the other hand, when energy flows from the electric powertransmission lines 40 to the electric power transmission lines 50, theprice setting apparatus 30 raises the selling price of electric powerhaving been set at present, and notifies the selling price to the 99numbers of nodes 2. However, when the price-is close to the price ofelectricity that can be supplied by another means, such as a means forobtaining electricity from a thermal electric power station or the likethrough the electric power transmission lines 40, the selling price ofelectric power is not raised.

[0080] In the case when the electric power generation cost at each ofthe 99 numbers of nodes 2 is lower than the selling price of theelectric power, the output of its own electric power generator is raisedor the electric power generator is activated, whereby the sale ofelectric power can be started. This can promote the sale of electricpower from the region to which electricity is supplied from thesubstation 10.

[0081] As described above, the amount of energy (electric power) passingthrough the substation 10 decreases, whereby the electric powertransmission loss between substations or between a substation and anelectric power station can be reduced. Furthermore, this relation issimilar to the relation among a substation 110, an ammeter 120, a pricesetting apparatus 130, the electric power transmission lines 40, theelectric power transmission lines 150 and nodes 101 in another group. Inother words, by dividing a plurality of nodes into a plurality of groupsand by balancing the supply and demand of electric power in each group,it is possible to reduce the electric power transmission loss of thewhole system.

[0082] In the case when the difference between the price set by theprice setting apparatus 30 and the price set by the price settingapparatus 130 is larger than the total electric power transmission lossof the substation 10, the electric power transmission lines 40 and thesubstation 110, the price at each node may be set referring to thepreset price at another node. For example, in the case when the priceset by the price setting apparatus 130 becomes larger than the sum ofthe price set by the price setting apparatus 30 added to the totalelectric power transmission cost of the substation 10, the electricpower transmission lines 40 and the substation 110, the selling price ofelectric power is set as described below.

[0083] (1) When electric power flows from the electric powertransmission lines 40 to the electric power transmission lines 50, theprice setting apparatus 30 raises the selling price of electric power.

[0084] (2) When electric power flows from the electric powertransmission lines 150 to the electric power transmission lines 40, theprice setting apparatus 130 lowers the selling price of electric power.

[0085] (3) In the cases other than the cases (1) and (2), and in thecase when the total of the amount of electric power flowing from theelectric power transmission lines 40 to the electric power transmissionlines 150 (this becomes a minus value when electric power flows from theelectric power transmission lines 150 to the electric power transmissionlines 40) and the amount of electric power flowing from the electricpower transmission lines 40 to the electric power transmission lines 50is larger than zero, the price setting apparatus 30 raises the sellingprice of electric power. (4) In the cases other than the cases (1) and(2), and in the case when the total of the amount of electric powerflowing from the electric power transmission lines 150 to the electricpower transmission lines 40 (this becomes a minus value when theelectric power flows from the electric power transmission lines 40 tothe electric power transmission lines 150) and the amount of electricpower flowing from the electric power transmission lines 50 to theelectric power transmission lines 40 is larger than zero, the pricesetting apparatus 30 lowers the selling price of electric power.

[0086] In the above-mentioned embodiment, the supply and the demand ofelectric power are balanced by changing the selling price of electricpower used as information for increasing/decreasing the amount ofelectric power supply; however, the supply and the demand may bebalanced by changing the purchase price of electric power used asinformation for increasing/decreasing the amount of electric powersupply or by changing both the selling price and the purchase price ofelectric power used as information for increasing/decreasing the amountof electric power supply.

[0087] Embodiment 3

[0088]FIG. 3 is a view showing the configuration of an electric powersupply and demand management system in accordance with Example 3 of thepresent invention. Example 3 shown in FIG. 3 is the same as Example 1 inthat each node has electric power consuming apparatuses, an electricpower generator and a storage battery, but different in that theelectric power selling/purchasing system 7 used as a second calculationunit determines the selling price of electric power.

[0089] The electric power selling/purchasing system 7 sets the sellingprice of electric power on the basis of information, such as the currentelectric power supply capacity and the electric power storage amountstored in the storage battery. For example, the selling price ofelectric power may be set by subtracting a constant value from a limitcost per unit of electric power of the present electric power generator,or the selling price of electric power may be set lower on the basis ofthe electric power storage amount of the storage battery when theelectric power storage amount is large.

[0090] The electric power selling/purchasing system 7 convertsinformation for identifying the node to which the system itself belongsand information regarding the selling price of electric power and thesalable amount of electric power into pulse signals and transmits thesignals as electric power selling bid information to the electric powertransmission system 3. The electric power selling bid information iscollected at one location or at each region and received by nodes orelectric power suppliers demanding electric power; these nodes andelectric power suppliers competitively transmit electric power sellingrequest information (successful bid information) to the node thattransmitted the above-mentioned electric power selling bid information.

[0091] In other words, in the electric power supply and demandmanagement system of the present invention, a node requiring electricpower compares the selling prices of electric power presented byelectric power suppliers and other nodes capable of selling electricityfrom their electric power generators, thereby being able to acquireelectric power at a lower price.

[0092] An example of a method of retrieving bid information stating thata node requiring electric power purchases (is supplied with) electricpower at a low price will be described. For example, a table comprisingbid information including the identification number of each node,selling price of electric power and salable amount of electric power isprepared as shown in FIG. 4. The node requiring electric power is thensubjected to the following processing.

[0093] First, values are obtained by dividing the selling price ofelectric power at each node capable of selling electric power by itselectric power transmission efficiency, and a node X having the minimumvalue is found out. The electric power transmission efficiency can beobtained by (the amount B of electric power receivable by a node thatreceives electric power)/(the amount A of electric power transmitted bya node that sells electric power). Furthermore, the increase of theamount of electric power, which is converted into heat owing to changein current, the resistance of transmission lines and the like duringelectric power transmission from an electric power selling node to anode requiring electric power, becomes A-B.

[0094] In the case when the amount of electric power that can besupplied (sold) by the node X is larger than the value obtained bydividing the amount of electric power, which is required by a nodedemanding electric power, by the electric power transmission efficiency,a value obtained by dividing the required amount of electric power bythe electric power transmission efficiency is added to the sellingamount of electric power (bid information) requested to the node X.

[0095] On the other hand, in the case when the amount of electric powerthat can be supplied (sold) by the node X is smaller than the valueobtained by dividing the amount of electric power, which is required bya node demanding electric power, by the electric power transmissionefficiency, the amount of electric power that can be supplied is addedto the selling amount of electric power (bid information) requested tothe above-mentioned node X.

[0096] The required amount of electric power can be obtained by ((theamount of electric power required by a node demanding electricpower)−(the selling amount of electric power requested to a node sellingelectric power))×(electric power transmission efficiency).

[0097] Next, a similar calculation is carried out for nodes whereinvalues obtained by dividing the selling prices of electric power by theelectric power transmission efficiency are small, and this calculationis repeated until the required amount of electric power becomes zero.After the above calculation is completed for all nodes demandingelectric power, the selling amounts of electric power (bid information)are transmitted to all the nodes requesting the sale of electric powervia the electric power transmission system. Hence, electric power issold to nearby nodes demanding electric power, whereby the sale andpurchase of electric power can be done efficiently.

EXAMPLE 4

[0098]FIG. 5 is a view showing the configuration of an electric powersupply and demand management system in accordance with Embodiment 4 ofthe present invention. Embodiment 4 shown in FIG. 5 is the same asEmbodiment 1 in that each node has electric power consuming apparatuses,an electric power generator and a storage battery, but different in thatthe operation of the electric power selling/purchasing system isdetermined depending on voltage by using the fact that the voltagechanges depending on electric power supply and demand situation. Inother words, the voltage lowers when electricity is supplied to a nearbynode via the transmission lines, and the voltage rises when electricityis supplied reversely; hence, electric power may be sold when thevoltage is low, and electric power may be prevented from being sold whenthe voltage is high.

[0099] More specifically, the electric power selling/purchasing system 7determines as to whether electric power is sold or not depending on theelectric power storage amount at the storage battery 5 and the voltagesignal from a voltmeter 9, and also determines the amount of electricpower to be sold, and then sell the electric power. As a result,electric power can be sold when electric power is demanded near thenode, whereby electric power can be used efficiently as a whole in theelectric power supply and demand management system.

[0100] In addition, when distributed processing is carried out at eachnode as in the example, even if an accident occurs, for example if apart of the electric power transmission lines of the electric powertransmission system is cut off, the electric power supply and demandmanagement system is controlled so that supply and demand are balancedautomatically at portions connected by the electric power transmissionlines, thereby being advantageous.

[0101] In the case when the voltmeter 9 does not operate accurately,there is danger that nodes selling electric power might be concentratedon limited nodes. For example, in the case when it is set that electricpower is sold when the voltages of the electric power transmission linesconnected to two adjacent nodes are almost the same and when thevoltages at the two nodes are constant (for example 100 V) or more, theselling of electric power from the node, the measured voltage of whichis slightly lower, has higher priority.

[0102] To solve the above-mentioned problem, electric power should besold by further considering the amount of electric power stored in thestorage battery or the voltage should be measured accurately. FIG. 6 isa view showing the configuration of an example of a circuit formeasuring the voltage accurately. In FIG. 6, reference voltage (thedesirable voltage of the electric power transmission lines) lines 3 b aswell as electric power transmission lines 3 a in the electric powertransmission system are connected to the voltmeter 9 of each node. Aswitch S1 and a switch S2 are switches for connecting the electric powertransmission lines 3 a or the reference voltage lines 3 b to a rectifier9 a. Alternating current from the electric power transmission lines 3 aor the reference voltage lines 3 b is rectified to direct current by therectifier 9 a and converted into a digital signal representing a voltageby an analog/digital converter 9 b. A control circuit 9 c transmits avoltage signal obtained by dividing the voltage value across theelectric power transmission lines 3 a by the reference voltage value tothe electric power selling/purchasing system 7. Since the electric powertransmission lines 3 a and the reference voltage lines 3 b are measuredby using the same rectifier 9 a and the analog/digital converter 9bid ispossible to obtain signals wherein errors due to variations in parts andthe like are cancelled.

[0103] Embodiment 5

[0104]FIG. 7 is a view showing the configuration of an electric powersupply and demand management system in accordance with Embodiment 5 ofthe present invention. In the electric power supply and demandmanagement system of this embodiment, twp nodes 101 and 201 are includedin one group. In FIG. 7, a fuel cell 104 and a fuel cell 204 used aselectric power generators are shown separately from the node 101 and thenode 201, respectively, for the sake of convenience; however, they areincluded in the node 101 and the node 201, respectively, actually.

[0105] Furthermore, when the amounts of electric power consumption atthe nodes are measured by electric power distribution boards 102 and202, respectively, as shown in FIG. 7, an electric power consumingapparatus, which receives electric power supplied from the correspondingdistribution board, or a set of such electric power consumingapparatuses becomes a node; this is advantageous in that the amounts ofelectric power consumption of the electric power consuming apparatuses,which are physically adjacent to each other, that is, have the sameelectric power transmission loss on the basis of a certain fuel cell,can be measured together. For example, nodes having higher electricpower transmission efficiency by electric power transmission from thefuel cell 204 rather than by electric power transmission from the fuelcell 104 can be measured together by a wattmeter 203. The amounts ofelectric power consumption of the node 101 and the node 201 are measuredby a wattmeter 103 and the wattmeter 203, which are measurement means,respectively.

[0106] The wattmeter may perform measurement by counting the number ofrevolutions of a disc, which rotates depending on the amount of electricpower consumption, or by calculating the sum of current values, whichare obtained by measuring current or the like, with the use of an ADconverter at constant time intervals. Data measured by the wattmeter 103and the wattmeter 203 is transmitted to a storage means 301, which is astorage unit, and stored therein.

[0107] The storage means 301 memorizes the amount of electric powerconsumption in every time zone as a table as shown in FIG. 8, forexample. Since the capacity of the storage means 301 is limited, whenthe free space of the storage area thereof is lost or becomes small, newdata (current data) is stored while older data is deleted. The datarecorded in the storage means 301 is read by predicting means 302 andused as a parameter for predicting the amount of electric powerconsumption. The first calculation unit or the second calculation unitmay be used to function as the predicting means 302 and supplied amountdetermining means 303.

[0108] The amount of electric power consumption is predicted asdescribed below. For example, when the node is a general household andno data is available in the storage means 301 (for example, immediatelyafter the control apparatus is installed), a standard electric powercharge obtained depending on the number of family members, familystructure, season, etc. is used as it is. When data for one or more daysis stored in the storage means 301, the amount of electric powerconsumption can be predicted by averaging data in the same time zone.Furthermore, the hour of rising and the number of family members at homeare different depending on weekday or holiday; therefore, the amount ofelectric power consumption can be predicted accurately by averaging pastelectric power charges depending on weekday, holiday or a day of week.

[0109] In addition, the amounts of electric power consumption of an airconditioner and the like differ depending on the season; hence, theamounts of electric power consumption can be predicted highly accuratelyby averaging the amounts of electric power consumption every season, bydeleting the data of the amounts of electric power consumption in acertain period of the past or by not using the data of the amounts ofelectric power consumption in a certain period of the past when takingan average. Furthermore, the amounts of electric power consumptiondiffer depending on weather; hence, the amounts of electric powerconsumption can be predicted highly accurately by averaging the amountsof electric power consumption depending on the weather conditions.Moreover, the amounts of electric power usage differ depending on theschedule information of each day (for example, nobody at home because oftravel, no school because of summer vacation, returning home late,visitors at home, etc.); hence, the amounts of electric powerconsumption can also be predicted highly accurately by dividing theschedule information into a plurality of categories and by taking anaverage for each category.

[0110] The categories are assumed to be weekday and holiday; spring,summer, fall and winter; school day or no school day; weather; visitorsat home or not; plan to go out; plan to take a bath; and othersituations affecting the amounts of electric power consumption and thecombinations of them. The schedule information may be input from apersonal computer or the like, which is used as a control unit formanaging a schedule at each node and connected to the electric powersupply and demand management system, or may be received from theelectric power supplier.

[0111] Furthermore, information estimated from the amount of electricpower consumption in the morning or the like may be used as the scheduleinformation. In other words, for example, since the hour of rising islate during a holiday, if the amount of electric power consumption,which would begin to increase at a certain time of the day in the caseof a weekday, remains small, it may be judged that today is a holiday;or it may be judged that nobody is at home if the home security systemis in its absent mode.

[0112] Moreover, the amounts of electric power consumption of the pastmay be categorized as described above and they may be reflected to theschedule information; furthermore, the amount of electric powerconsumption predicted as described above may be changed by using theschedule information. For example, in the case when a resident was notat home until 18:00 and he returned at 18:00, an air conditioner or thelike is turned on, whereby the amount of electric power consumptionincreases usually; hence, the final amount of electric power consumptionmay be obtained by averaging the amounts of electric power consumptionof the past in the case when he is at home all day and by adding theamount of electric power consumption predicted to increase (the amountof increase) to the average.

[0113] The amount of increase to be added differs depending on season;hence, it may be based on data prepared for each category, may beobtained from a predetermined calculation formula by using a parameteraffecting the amount of electric power consumption, such as temperatureand weather, or may be obtained by averaging actual measurement values.

[0114] The above-mentioned actual measurement values are obtained asdescribed below, for example. Namely, the average of the actualmeasurement values of the amounts of electric power consumption in thecase when the resident is at home all day and the actual measurementvalue of the amount of electric power consumption during a certain timehaving passed after the resident returned home in the middle of the dayare obtained, and the difference between the above average value and theactual measurement value is memorized. The average of the differencesobtained in the same manner in the same category is used as the amountof increase to be added. As described above, the supplied amountdetermining means 303 determines the supplied amount of electric poweron the basis of the amount of electric power consumption predicted bythe predicting means 302.

[0115] Since two fuel cells are used in the electric power supply anddemand management system shown in FIG. 7, the supplied amount ofelectric power from each fuel cell differs depending the characteristicof the fuel cell and an electric power transmission loss between thefuel cell to the node. In the case when the node 101 is distant from thenode 201 and when an approximate efficiency is determined by theelectric power transmission loss between the node 101 and the node 201,the predicted amounts of electric power consumption at the node 101 andthe node 201 may be used directly as the supplied amounts of electricpower of the fuel cell 104 and the fuel cell 204 as a general rule.Furthermore, in the case when the amount of electric power consumptionpredicted at each node exceeds the electric power supply capacity of itsfuel cell, electric power may be supplied from the fuel cell of theother node.

[0116] For example, in the case when the output of the fuel cell at oneof the nodes is small, the characteristic of the fuel cell is efficientand the electric power transmission loss between the node 101 and thenode 201 is small, both the fuel cells may always be activated, wherebythe electric power may be distributed to the two nodes equally. In otherwords, a plurality of fuel cells are activated and managed in a groupand necessary electric power is supplied to the nodes in the group. Inthis case, the amount of electric power consumption measured by thewattmeter 103 may be added to that measured by the wattmeter 203, andthe total may be stored in the storage means 301.

[0117] On the other hand, in the case when the output of the fuel cellat one of the nodes is large, the characteristic of the fuel cell isefficient, the electric power transmission loss between the node 101 andthe node 201 is small and necessary electric power can be supplied onlyby activating one of the fuel cells, only the fuel cell belonging to thenode, wherein the predicted amount of electric power consumption islarger, may be activated to supply electric power.

[0118] Alternatively, data representing the relation between the outputof an electric power generator and the usage amount of fuel (forexample, data shown in FIG. 10) may be memorized, and the most suitableamount of electric power generation of each fuel cell may be obtained bycalculation or simulation from the memorized content. Furthermore, sincethe amount of change per hour in the amount of electric power supply ofthe fuel cell has a limit, the amount of electric power supply may bedetermined so that the amount of the change is a predetermined value orless.

[0119] Next, a supply control means 304 operated valves 105 and 205 forfuel, such as gas depending on the supplied amount determined by thesupplied amount determining means 303. Since the output of the fuel celldoes not increase immediately after the valve for fuel, such as gas, isopened, the amount of operation of the fuel valve is determined on thebasis of the amount of electric power supply for the next two hours.Furthermore, in the above-mentioned embodiment, the amount of electricpower consumption once measured is memorized, the memorized content isread and the amount of electric power consumption is predicted; however,the method described below may also be used.

[0120] Namely, the standard amount of electric power consumption for aday is memorized in the storage means 301 first. When the measurementresult of the amount of usage is received, z=ay+x(1−a) is obtained byusing the amount x of electric power consumption at that time and theamount y of electric power consumption measured at the present time fromthe contents memorized in the storage means 301, and z at that time ismemorized instead of x in the storage means 301 (a is a predeterminedcoefficient satisfying the relation 0<a<1).

[0121] The amount of electric power consumption can be predicted byusing the contents stored in the storage means 301. In this manner,averaging can be carried out while highly weighting measurement data,which are obtained at times close to one another, thereby beingadvantageous in that only a small amount of storage capacity isrequired. Furthermore, in the above-mentioned embodiment, the amount ofelectric power consumption was measured and the amount of electric powerconsumption was predicted by using the measurement value; however, it isnot always necessary to measure the amount of electric powerconsumption, but the standard amount of electric power consumption maybe directly used as the predicted value of the amount of electric powerconsumption.

[0122] Still further, in the above-mentioned embodiment, a case whereinfuel cells are controlled was explained; however, the electric powergenerators are not limited to the fuel cells, but other types ofelectric power generators, such as gas turbines, may be controlled. Thepresent invention is particularly effective when controlling an electricpower generator that cannot change its amount of electric power supplyin a short time.

[0123] Embodiment 6

[0124] The above Embodiment 5 in accordance with the present inventioncan be attained with the use of circuits; however, the present inventioncan also be attained with the use of a CPU, memory and peripheralcircuits. In this case, the flowchart of a program for determining theoperation of the CPU is shown in FIG. 9. Step 1 is to realize thestorage means 301, step 2 is to realize the predicting means 302, step 3is to realize the supplied amount determining means 303, and step 4 isto realize the supply control means 304. These steps are not alwaysrequired to be carried out in the above order. Furthermore, operation iscarried out at intervals of 10 minutes in FIG. 9; however, the operationmay be carried out at intervals other than 10 minutes, and the operationmay be carried out at intervals different from one another.

[0125] For example, step 1 to step 4 may be carried out as fourprocesses independent from one another. In other words, process 1 andprocess 4 may be carried out at intervals of 10 minutes, and process 2and process 3 may be carried out in time zones (for example at night)during which the CPU is idle.

[0126] Furthermore, programs (any programs, such as source programs,object programs, etc., regardless of the type of execution) foractivating the CPU are stored on a recording medium that can be read bya computer, and then transferred (sold), or only the contents of theprograms are distributed via communication lines, and the contents arefinally stored in memory constituting an electric power supply controlapparatus, whereby the electric power supply control apparatus can berealized.

INDUSTRIAL APPLICABILITY

[0127] The present invention can provide an electric power supply anddemand management system and energy management system capable ofefficiently controlling and managing the supply and demand of electricpower while reducing electric power transmission loss by selecting anode that can sell electric power from the electric power generatorthereof to an electric power supplier depending on the demand of thenode.

[0128] Furthermore, the present invention can provide an electric powersupply and demand management system that can allow a fuel cell used asan electric power generator to generate an appropriate amount ofelectric power, not excessive or lacking.

1. An electric power supply and demand management system including anelectric power supplier, an electric power transmission system, andelectric power consuming nodes, each of which having an electric powergenerator, connected to said electric power transmission system andclassified into a plurality of groups, characterized by comprising, afirst calculation unit for obtaining a difference between a total ofelectric power supplied from said electric power supplier to said nodeor group and a total of electric power consumed by an electric powerload of said node or group, and a first transmission unit fortransmitting information for increasing/decreasing an amount of electricpower supply to said electric power supplier so that said differencebecomes smaller.
 2. The electric power supply and demand managementsystem in accordance with claim 1, characterized in that said firstcalculation unit determines at least one of a selling price of electricpower from said electric power supplier to said node or group and apurchase price of electric power from said node or said group to saidelectric power supplier, by using said difference between a total ofelectric power supply from said electric power supplier to said node orgroup and a total of electric power consumed by an electric power loadat said node or group as a parameter, and said first transmission unittransmits at least one of said selling price and said purchase price tosaid node or group.
 3. The electric power supply and demand managementsystem in accordance with claim 1 or 2, characterized in that saidelectric power supplier has a reception unit for receiving informationselected from the group consisting of an electric power charge, anamount of electric power consumption and an electric power supplycapacity of said node or said group, said first calculation unitdetermines an amount of electric power and a purchase price of electricpower demanded by said electric power supplier for each node, which cansell electric power among said nodes, on the basis of said information,and said first transmission unit transmits at least one of said amountof electric power and said purchase price demanded by said electricpower supplier to said node.
 4. The electric power supply and demandmanagement system in accordance with claim 1 or 2, characterized in thatsaid node or said group is provided with; a second transmission unit fortransmitting information selected from the group consisting of anelectric power charge, an amount of electric power consumption and anelectric power supply capacity to other nodes, groups or said electricpower supplier; a second reception unit for receiving informationselected from the group consisting of an amount of electric power, apurchase price of electric power and a selling price of electric powerdemanded by said other nodes, groups or said electric power supplier;and a control unit for controlling an output of said electric powergenerator of said node on the basis of said information.
 5. The electricpower supply and demand management system in accordance with claim 4,characterized by comprising a node information storage unit for storingnode information including a node identifier for identifying said nodeand an amount of electric power consumption and an amount of electricpower supply of said node identified by said identifier, andcharacterized in that said first calculation unit calculates an amountof transmittable electric power from one node to other nodes and/or saidelectric power supplier by using said amount of electric powerconsumption and said amount of electric power supply included in saidnode information as parameters, said first transmission unit transmits asignal indicating said amount of transmittable electric power to eachnode, and said node transmits said transmittable electric power to theother nodes and/or said electric power supplier.
 6. The electric powersupply and demand management system in accordance with any one of claims1 to 5, characterized in that said electric power supplier has asubstation, said first calculation unit calculates a purchase amount ofelectric power and a purchase price of electric power, which aredemanded by said electric power supplier, by using electric power supplyand demand information regarding a flowing direction and an amount ofenergy between a high-voltage side to a low-voltage side of saidsubstation, and said first transmission unit transmits said amount ofelectric power to be purchased and said purchase price to said node orsaid group.
 7. The electric power supply and demand management system inaccordance with any one of claims 1 to 6, characterized in that saidnode is provided with a storage battery, and a second calculation unitfor determining at least one selected from the group consisting of apurchase amount of electric power, a purchase price of electric power, aselling amount of electric power and a selling price of electric power,which are demanded for said other nodes, by using information regardingelectric power demand and storage amounts of storage batteries connectedto other nodes, and said second transmission unit transmits at least oneselected from the group consisting of a purchase amount of electricpower, a purchase price of electric power, a selling amount of electricpower and a selling price of electric power to at least one of saidelectric power supplier and the other nodes.
 8. The electric powersupply and demand management system in accordance with any one of claims1 to 7, characterized in that said first calculation unit or said secondcalculation unit predicts an amount of electric power consumption ofsaid node or said group and determines an amount of electric powersupply, which is demanded by said node or said group, by using saidpredicted amount of electric power consumption as a parameter, and saidfirst transmission unit or said second transmission unit transmits asignal in order for an electric power generator of a node or a groupother than said node or said group, or for said electric power supplierto supply said amount of electric power.
 9. The electric power supplyand demand management system in accordance with any one of claims 1 to8, characterized by comprising electric power consumption amount storagemeans for storing information regarding an amount of electric powerconsumption of each node, and characterized in that said firstcalculation unit or said second calculation unit predicts an amount ofelectric power consumption of each node or each group by using saidstored amount of electric power consumption as a parameter.
 10. Theelectric power supply and demand management system in accordance withclaim 8 or 9, characterized in that said first calculation unit or saidsecond calculation unit determines an amount of electric power supplyfrom said node by using data including a relation between an output ofsaid electric power generator and an amount of fuel consumption asparameters.
 11. The electric power supply and demand management systemin accordance with claim 8, 9 or 10, characterized in that said firstcalculation unit or said second calculation unit determines an amount ofelectric power supply from said electric power generator by using atleast said amount of electric power consumption of said node as aparameter.
 12. The electric power supply and demand management system inaccordance with claim 11, characterized in that said first calculationunit or said second calculation unit determines an amount of electricpower supply of each electric power generator so that the number ofelectric power generators in operation of said nodes becomes minimum ormaximum.
 13. The electric power supply and demand management system inaccordance with claim 11 or 12, characterized in that said firstcalculation unit or said second calculation unit predicts an amount ofelectric power consumption of each node by using schedule information.14. The electric power supply and demand management system in accordancewith claim 11, 12 or 13, characterized in that said first transmissionunit or said second transmission unit transmits information forincreasing/decreasing an amount of electric power supply from saidstorage battery of said each node or said electric power generatorconnected to said storage battery to a node, which requires electricpower, by using information regarding a storage amount of said storagebattery or information regarding a transfer amount of energy of eachnode.